Helicopter energy management is of primary concern during an engine out situation onboard a helicopter. Energy may be found within each of the rotating components including the kinetic energy stored in the rotor system. This energy may be used to counteract the rate of descent during an autorotation landing by converting the kinetic energy in the rotor system into Lift. Additional Lift is produced at the bottom of an autorotation by increasing the angle of attack of the main rotor blades. During the autorotation procedure, rotor RPM will rapidly decay. It is essential to properly time the autorotation flare by converting the rotor RPM energy into Lift to fully arrest the descent and cushion the landing.
Traditional flight director systems may offer guidance to a ground based navigational aid including an instrument landing system (ILS) or area navigation (RNAV) lateral and vertical guidance profiles. These systems, however, offer guidance to a specific point on the surface and fail to incorporate local atmospherics into the guidance equation. For example, and ILS may provide ground based guidance to a specific landing point on a runway. Similarly, RNAV systems may offer inertial or satellite based guidance to a specific point on a runway. These systems have no value during an engine out autorotation maneuver.
Proper autorotation technique is of primary concern, since the pilot has a single opportunity for success. Pilot visual scan should be appropriate for the phase of the autorotation to be successful. As the pilot turns the helicopter to final landing heading or course line prior to the flare, pilot scan should focus almost entirely outside. The successful scan should include: 1) Outside—to the horizon for attitude, ground track, and nose alignment; 2) Down—for altitude to set the flare and for closure vertical speed and groundspeed; and 3) Inside the cockpit—to cross-check airspeed, rotor rpm, and engine rpm in the descent.
The completion maneuver just before the helicopter touches down may be referred to as the autorotational flare. Each autorotational flare may be unique depending on the existing wind conditions, airspeed, Density Altitude (DA), and the aircraft gross weight. These many variables could lead to pilot misinterpretation of existing conditions and an unsuccessful autorotation. Therefore, a need remains for a system and related method to aid a pilot in recognition of these variables and offer cues to mitigate factors which could lead to an unsuccessful autorotation.